Quote:
Originally Posted by rogerg
I think with adaptive optics they usually distort the secondary not the primary, so it's the 6m they'd be distorting here not the 42m. Still quite a challenge though, I bet.
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Actually it's the primary, at least thats what they do at VLT. But given that E-ELT's secondary is similar in size to VLT's primary then it's probably a good bet that they will apply AO to the secondary in this case. Then on the other hand it might be easier to physically distort a mirror with a larger surface - the required accuracy must be less and they can put more actuators under a larger mirror. I'm just guessing though...
I took these photos at VLT a couple of years ago. Notice how the primary is full of actuators on the back side, I thought it looked very cool

Also notice how dusty that mirror is! The reflection looks rather dull, it must have been right before its yearly resurfacing.